Discussion in 'Speakers' started by Zilch, Feb 23, 2008.
Yah, well, we'll see soon enough....
Hey Zilch.. I'm gonna direct your attention to here... http://www.audiokarma.org/forums/showthread.php?t=276485
I figure now that I've got the ball rolling, I'll quit taking up valuable space in this thread... and drive you crazy in my own
Oh.. anyone else that needs a laugh a day is more than welcome to interject your laughs over there too...
sorry, I missed the fact you already had the DC 300s! opps.
See Wayne Parham's posts relating to vertical patten control in this thread describing the nature of the forward lobe and the nulls in the response which define it. The objective is to optimize the location of the forward vertical axis such that the response is uniform at and about the desired listening axis.
We've discussed the issue of interference when multiple sources are playing the same program material many times in this forum in different contexts such as stacking speakers and otherwise using multiples in the same acoustic space. The same problems arise in a more limited fashion with every multi-way speaker design, as the several drivers are playing the same frequencies in the crossover region, and thus interfere with each other.
In individual loudspeakers, this occurs in a predictable manner, and with this recent work, we are discovering and defining the consequences, and manipulating them to maximum advantage in eWave designs for specific combinations of drivers and waveguides. It's a sophisticated system refinement which enhances performance over simply sticking drivers in a box, and eWave's controlled directivity affords us the opportunity of employing it to considerable advantage.... :thmbsp:
Yeah, Exactly what he said..
1) Heavy fill, tune to 30 Hz with 2 x 2" ports 9" long.
2) HF polarity inverted from standard eWave connection.
XO = 1.8 kHz
Forward axis = 1" or arctan 1/44 = 1.30° above midpoint between drivers w/D2500Ti-Nd.
Thanks for the summary Zilch. That was a concise given the wealth of info.
But given the summary, is the revised DC300 crossover specifically tailored to the PE Trap Cab? I ask because it does seem like the cab is a bit small for the DC300. I even seem to remember some Zilch guy mentioning that way back when the trap cab iterations were starting. The VAS for the DC300 is 133 liters.
You mean the "Image Rendition Zone," of course....
Yes, there are compromises. The objective is slam-dunk off the shelf, and even in this "too-small" cab, DC300 has usable bass (-6 dB) down to somewhere between 35.5 and 38.5 Hz according to the BB6P sims, depending upon whether measured (violet) or published T/S parameters are used for the calcs.
More net volume may be achieved by moving the baffle forward as Jack and Skywave have done, which Gordon advises will achieve even better performance. I'll likely be studying that, as well, but it is very good as shown, as may be seen in the documentation I have posted.... :thmbsp:
When the music is playing via the ECW's does the IRZ encompass the dinner table?
E'Wave's IRZ encompasses all of Earth's continents but Antartica.
[Which isn't always counted as one.... ]
driver positioning question
I see considerable vertical distance between the woof and the WG. I'm guessing you made the WG cutout so the WG would clear the woofer frame when both were front mounted. If you had planned for rearr mounting the woof would you have placed the WG closer to it or would tha tchange be irrelevant?
Further, is the woofer mounted directly to the baffle or is there a spacer?
Increasing the cab volume could be easily achieved by front mounting a new baffle over the edges of the sides (rather than inset) IF the edges of the sides were parallel. Unfortunately the tapered sides present non-parallel edges at the front. I might still be tempted to try.
I'll have a pair of mahogany Jensen cabs coming over on Saturday. These might end up as Ewaves. On Sunday the NLA cabs will be back from refinishing and will be queued up for ewaving. At this rate I'll never get the DQ-10s done.
Recall that the QSC waveguide spans the distance between the woofer opening and the top edge, placing the centers at 10.5". With each of these iterations, I am placing the different waveguides in the same location, removing that as a variable in comparing their performance.
Yes, the vertical lobe would be taller if I placed them closer together, but thus far, I have been able to achieve a stable and well-aimed +/- 10° forward lobe with three different waveguides installed at this location, and good baffle aesthetics. :yes:
There is no speaker ring back there; it is direct-mount. This presents issues for rounding over the opening, but the answer is simple -- mount using clamps, which moves the mounting hardware outside the roundover circle. I hope to get that done this weekend so I can determine if the edge of that opening, which I believe is appearing in the response curves, should be treated.
Jack and Skywave have both moved it flush front, but face-mounting is also an option, attending to the detail of the small angle on the edge at that location, to expand the net internal volume even more. Edge rounding is an option in both cases. I'm working with the standard cab to establish the baseline for variants such as moving the baffle forward incrementally.
We're having this discussion on two other forums with respect to whether the substantial 1.125" overhangs at the cabinet edges are as problematic as the common wisdom presumes. I have made a substantial case that constant directivity waveguides obviate that, as the edges are not illuminated by the controlled forward wavefront. We'll see; I am not alone in this thesis....
Point source waveguide...
I noticed BMS is calling this 12" coax a waveguide....80x60...:scratch2:
They've got the waveguide part correct, looks like, but it potentially shadows the mids from the woofer cone; that's one hell of a hole at 1.6 kHz.
GPA did similar with their 12" duplex, and perhaps a better job of it, but whether either of them actually works worth a whit is another question....
Wanted to thank David for the beautifully restored cabs. James for picking his brain, and Zilch for the awesome setup, and putting up with all my "rookie" PM's. They sound really good. Not sure the best way to describe them, the highs are very detailed but not harsh.
After some listening I do know I can benefit from some better woofers, but they still sound damn good.
-Altec Valencia Cabinents
-Kenwood Trio 777 Woofers
-Selenium Drivers w/Pyle Horns
Next is to make some grills for them.
Damn!.. those came out REALLY NICE TODD.. Can't wait to hear them next weekend.. .
One question though.. is that woofer meant to be in a sealed cab, or do you have the ports in the back? Do you know what the cab is tuned to? That could be some of the issue of the mids you were telling me about...
In beautiful Valencia cabinets, Rygen is "Official AK E'Waver" #82.... :thmbsp:
Ya, if you recall, I knew going into this they may not be the optimal setup, but it got them in one piece and they were just laying around. The Trio 15" used in the 777's is used in a 3 and 4 way design, and it is ported (I know cause my Dad has a pair).
From what I researched, there are two versions of the Val's, one with a sealed cab, and another with 1 or 2" ports on each side of the horns, in the shape of rectangles.
But yes, tweaking is indeed next.
Thanks man, appreciate your help.
There were no sealed Valencias. 846A had port openings either side of the horn, and 846B, two round ports down by the woofer.
Whether these should be ported or not depends upon the woofer parameters. If they were originally used in ported cabinets, then chances are they should be ported here, as well, for the optimum bass response. Unless the T/S parameters for the woofers are known, the determination of the correct box tuning will have to be made empirically....
Separate names with a comma.